General
not block function, just confusing error tip message
Symptom
when customer add tracker name to vpn interface, but not add tracker definition in system template. will get confusing error tip message "Server error: Exception in callback". this not block any normal function, just for wrong tip message
Conditions
for feature template, when customer add tracker name ref to wan vpn interface or other template which depenency tracker, but not add tracker definition under system.
Workaround
if get error message "Server error: Exception in callback", both of step will effect:
1. can check if add tracker to lan vpn or wan vpn interface, and then check if tracker is add definition under system template
2. can use config group config again ,and for config group tracker ref is dropdown list, can't fill string name
Further Problem Description
not block function, just happens when customer add wrong config(add tracker string name to wan vpn interface ,but not add tracker definition), root cause is confusing error tip message
